The use of modern communication systems through which to communicate is a necessary aspect of modern society. Communication of data is required to effectuate many varied functions and services. The data that is to be communicated pursuant to such functions and services must sometimes be communicated, quickly and accurately, between widely dispersed locations.
Communication stations are positioned at the locations between which data is to be communicated. And, the communication stations are connected theretogether by a communication channel. Large numbers of users are able to effectuate many different types of communication services through use of many varied types of communication systems. And, as technological advancements permit, new types of communication systems have been developed and deployed. Some of the new types of communication systems permit existing communication services to be carried out more efficiently and some have made new types of communication services available. Technological advancements continue. And, new types of communication systems in which such technological advancements are deployed shall correspondingly be made available.
Technological advancements have, for instance, permitted the widespread deployment of communication systems that utilize digital communication techniques. Several advantages are provided by the use of digital communication techniques. Improved communication efficiencies are possible as a result of the use of digital communication technique. When digital communication techniques are utilized, data that is to be communicated is digitized into digitial form. Communication redundancies can be relatively easily removed from the data once the data is digitized.
By removing such redundancies, redundant data need not be communicated. And, as a result, the communication capacity of a communication system that utilizes digital communication techniques can be substantially increased relative to the communication capacity permitted in a corresponding communication system that utilizes only analog communication techniques.
A radio communication system is an exemplary type of communication system. A radio communication system is referred to as such because the communication channel that interconnects the communication stations in such a system is formed, at least in part, upon a radio link. That is to say, a radio link forms at least a portion of a communication path extending between the communication stations of the radio communication system. And, the data that is communicated between the communication stations is communicated upon the communication channel, referred to as a radio channel, defined upon the radio link
Use of a radio communication system by which to communicate provides various advantages. For instance, a radio communication system is generally more economically deployed than a wireline counterpart. The costs associated with the installation of the network infrastructure of a radio communication system is generally less than the costs associated with installation of the network infrastructure of a wireline counterpart. So, for reasons associated with initial-installation costs, deployment of a radio communication system is sometimes preferred over deployment of a wireline counterpart. Also, a radio communication system is implementable as a mobile communication system. And, mobility of communications is provided in a mobile communication system. Communications in a mobile communication system are possible, from and between, locations at which communications utilizing a conventional wireline communication system would be impractical. And, communications with a communication station as it is moving are sometimes also possible.
A cellular communication system is a type of radio communication system. Multiple access by significant numbers of users is permitted in a cellular communication system, and cellular communication systems have achieved high levels of usage, i.e., penetration, in many areas. The network infrastructures of cellular communication systems have been deployed throughout significant geographical portions of populated areas of the world. Successive generations of cellular communication systems have been developed and deployed using various communication technologies. And, successor-generation systems, intended to supplement and, eventually, to replace existing systems, also utilizing various communication technologies, are undergoing deployment or are under development.
Systems that were first-installed are referred to as being first-generation (1G) cellular communication systems. First-generation systems generally utilize conventional analog communication techniques and use frequency-division, multiple-access communication schemes. First-generation systems generally provide for circuit-switched, voice communications. Second-generation (2G) cellular communication systems, introduced subsequent to first-generation systems, generally utilize digital communication techniques and provide for some data services. 2.5G (second-and-a-half generation) and 3G (third-generation) systems are currently undergoing deployment. These systems, generally, provide for more extensive data services, e.g., such as services at higher data rates as well as services effectuable at multiple data rates. Successor-generation systems are under development. These systems are intended to provide opportunities for yet-further expanded communication services.
The GSM (Global System for Mobile communications) cellular communication system is an exemplary second-generation cellular communication service. An operational specification, promulgated by the ETSI (European Telecommunications Standards Institute), sets forth the operating protocols, and operational standards relating to operation of devices in such a system. The GSM system utilizes a combination of a frequency division multiple access (FDMA) and time-division multiple access (TDMA) communication schemes. Networks constructed to be operable pursuant to the GSM operating specification have been installed throughout many of the developed countries of the world. And, many millions of users subscribe to service in a GSM system to communicate telephonically therethrough. Other cellular communication systems, operable pursuant to other operating specifications have analogously been constructed.
Users communicate through the use of mobile nodes. The mobile nodes are regularly of physical dimensions permitting their hand-carriage by users of the mobile nodes. And, many mobile nodes are constructed to mimic operation of conventional telephonic stations. That is to say, many mobile nodes are operable both to originate and to terminate telephonic calls in manners that appear to the user to correspond to the manners by which a conventional, telephonic station is utilized to originate and to terminate such calls.
When a call is originated elsewhere for termination at the mobile node, signaling is generated with the mobile node during a call set-up procedure to cause an alert, such as a ringing tone, to be generated at the mobile node. The alert alerts the user of the mobile node of the call placement thereto. And, the user of the mobile node is able to accept the call in a manner analogous to the manner by which the user of a conventional wireline station takes the wireline station off-hook.
When a call is originated at the mobile node, the user enters the dialing digits that identify the station, i.e., the called party, at which the call is intended to be terminated, again in manners analogous to the manners by which the dialing digits associated with the called party are entered at a conventional wireline station. Call signaling procedures, generally transparent to the user, permit effectuation of the call with the called party.
Shortened dialing codes, herein sometimes referred to as short numbers or short dialing codes, are used to identify certain designated service centers in some areas. For instance, in the United States, some areas have 9-1-1, emergency service centers. The 9-1-1 code is sometimes referred to as an emergency number. In areas that have 9-1-1 service centers, when the 9-1-1 code is entered at a telephonic station, a call is routed to an appropriate 9-1-1 service center, thereby to facilitate emergency assistance responsive to the call. In other areas, such as the United Kingdom, an emergency services center is accessed telephonically from a telephonic station through the entry of a 9-9-9 code.
Other service centers are also designated by short numbers. For instance, directory service centers are accessed telephonically in some areas by entry of a 4-1-1 code at a telephonic station. And, in some other areas, a directory service center is accessed telephonically by entry of a 1-9-2 code. Also, operator assistance is accessed telephonically in some areas by entry of the digit ‘0’ and, in some other areas, by entry of the short code 1-0-0.
When the telephonic station at which the short code is entered is a mobile node, the mobile node might sometimes be positioned in an area at which a short code that designates a particular service center-type be of a first set, or sequence, of digits, and the mobile node might sometimes be positioned in an area at which the short code that designates the particular service center-type be of a different set, or sequence, of digits. For instance, the mobile node might initially be positioned in an area at which the short code associated with an emergency services center comprise the 9-1-1 digits and later positioned in an area at which the short code associated with the emergency service center comprise the 9-9-9 sequence of digits.
The home network associated with the mobile node, generally the network with which the user of the mobile node is familiar, therefore, might well use short codes that differ with the short codes that are used by the home network associated with the mobile node, i.e., the short codes with which the user is familiar or those that are stored, such as for speed-dialing purposes, at the mobile node.
If the short code associated with a service center that the user of the mobile node intends to call is entered at a location that utilizes a different short code to access the service center, the intended service center is not accessed.
A manner is needed, therefore, by which better to provide for placement of a call from a mobile node to a service center using a short code. That is to say, a manner is needed by which to take into account the mobility inherent of a mobile node so that a service center that is accessed by entry of a short code by a user of the mobile node remains accessible irrespective of the position of the mobile node when a call is placed to the service center.
It is in light of this background information related to communications in a radio communication system that the significant improvements of the present invention have evolved.